Good question. The DI is a processed signal with IR impulses to emulate a cabinet. Even the JP2C has this feature but not quite the same as the Cab clone used on the Mark VII. Both DI will have some sort of processing done to the signal. May not be ideal for sending to effects and then stereo out. It depends on the devices used in that chain. Any type of guitar effect probably will not be all that great with the DI output since most of them use an unbalanced TS type of input. XLR is a low impedance line level signal meant for recording purposes or for mixers so no micing of the cabinet is needed. You would have to convert the XLR that has a built in transformer that converts to unbalanced TS. That generally results in a different signal characteristic that may not be compatible with the FX units as it will be at a mic level than instrument level.
To be honest, I have yet to make use of the cab-clone or slave/line out features.
JP2C to interface with external FX and power amp, that would be the slave out. The equivalent on the Mark VII would be the line out. They seem to have similar descriptions. I would assume with both amps you can still use the speaker outputs to a cabinet. (for the MKVII that could be an external cabinet or if a combo, the onboard speaker). For the Mark VII if you want to disable the speaker output, do not have anything plugged into the speaker jacks as this connects an internal load resistor. For the JP2C, use the speaker off switch which will connect an internal resistor load. This is part of the Cab Clone interface. Just to not switch to speaker on without anything plugged into the speaker jacks. With either case, you can also make use of the FX loop and reverb on both amps along with the external processing and stereo amp. For both JP and MK7, Slave and Line out will also include the GEQ. Even the presence controls will have effect on the sound. Since both are driven from the output side of the OT, derived by the Cab-clone or by other means. JP2C does not seem to have a signal level control.
Mark VII (from the manual):
LINE OUT – DRY This ¼” buffered Output provides an unprocessed/uncompensated signal for feeding external IR Readers or recording a signal for re-amping. The CabClone IR processing will NOT be utilized here and the sound will contain all your gain, Tone, and EQ/REVERB/LOOP settings and processing, but will not resemble what you hear through guitar Cabinets or the CabClone’s XLR Direct Out. It will be much brighter and contain all the characteristics present BEFORE the treatment of the signal by guitar speakers and cabinets or the Models/IRs used in the CabClone IR derived from miking those. The LINE OUT signal level is determined by the INPUT LEVEL control and the signal level here will not be affected by the setting of the OUTPUT LEVEL control, which is dedicated to the CabClone IR’s XLR Balanced OUTPUT and the HEADPHONES Output. This is not a problem as any destination you are feeding with this output such as an IR Reader or Console or Interface will have its own Input Level control for optimization of incoming signals.
As for the JP2C (from the manual):
SLAVE A standard ¼” SLAVE Output provides a signal also captured from the SPEAKER Output, but in this case it is the raw, untreated signal. This is not to be confused with a “Shaped, EQ’d, Speaker Compensated or Impulse Response” signal/sound that would be appropriate for interfacing with a Console for either recording or live reinforcement. This signal is intended for adding additional power in live applications or driving processing racks for feed to additional (external) satellite amplifiers and cabs.
